I got a bold since one month now and happy with it. I know it has an old OS V4.6.0.190 , locked to Vodafone Egypt. Although I have upgraded all my prvious mobiles ( Imate, HTC, Samsung Omnia ) many times but I am reluctant to upgrade the bold. may be because I heard of the " White Screen if Death" , and also there is no fast way to send it for repair if needed.

Can some body poit out the main differnces between my OS and the recent one ?

Stability, performance enhancement, memory optimization, new features, bug fixes, battery optimization. Those are some of the standard improvements with new OS. There are very good instructions on how to upgrade and excellent help available if you run into issues. Go for it.